What is the most appropriate management for a 2-year-old boy with hypertrophic cardiomyopathy (HCM) and significant aortic stenosis, presenting with increased shortness of breath during physical activity?

Management of 2-Year-Old with Hypertrophic Cardiomyopathy and Severe Aortic Stenosis

This child requires urgent mechanical aortic valve replacement combined with septal myectomy (Option B). The combination of symptomatic severe aortic stenosis (68% stenosis) with hypertrophic cardiomyopathy and left ventricular hypertrophy in a 2-year-old presenting with worsening dyspnea represents a life-threatening dual left ventricular outflow tract obstruction that demands definitive surgical correction. 1

Rationale for Surgical Intervention

The presence of increasing dyspnea during physical activity indicates hemodynamic compromise from dual left ventricular outflow tract obstruction. 1 This child has two separate but synergistic obstructive processes:

• Fixed valvular obstruction from 68% aortic stenosis
• Dynamic muscular obstruction from hypertrophic cardiomyopathy with septal hypertrophy 1

The natural history of untreated severe aortic stenosis in children includes sudden death risk and progressive heart failure. 1 Medical management alone does not address the fixed valvular stenosis and is therefore inadequate. 1

Why Combined Surgical Approach is Necessary

When symptomatic obstructive hypertrophic cardiomyopathy coexists with valvular aortic stenosis requiring surgical treatment, surgical myectomy combined with valve replacement provides the opportunity to correct all structural and anatomic issues with a single procedure. 1

The modified Konno procedure has been reported to provide satisfactory long-term results for basal obstruction in young children, allowing for aortic valve replacement while simultaneously addressing the septal hypertrophy. 1 Transaortic septal myectomy adds minimal risk to other cardiac procedures, and relief of left ventricular outflow tract obstruction minimizes the risk of hemodynamic instability postoperatively. 1

Why Other Options Are Inappropriate

Option A (Reassure) - Dangerous and Contraindicated

• This child has symptomatic severe disease with worsening dyspnea, not mild or stable disease 1
• Untreated symptomatic aortic stenosis has worse survival than many cancers 2
• The combination of HCM and severe AS creates compounded risk for sudden death 1

Option C (TAVR) - Not Appropriate for Pediatric Patients

• TAVR is indicated for severe symptomatic aortic stenosis in patients with very high or prohibitive surgical risk 3
• This 2-year-old requires a valve that can grow with the child or be replaced as needed 1
• TAVR durability remains uncertain, particularly problematic in a child with decades of life expectancy 2
• Mechanical valve replacement is typically preferred in young patients to avoid multiple reoperations 1

Option D (Activity Restriction Alone) - Inadequate

• While activity restriction is appropriate for managing HCM symptoms in stable patients 1, this child already has symptoms at baseline activity levels, indicating advanced disease 1
• Activity restriction does not treat the underlying severe aortic stenosis 1
• Medical therapy with beta-blockers or calcium channel blockers is appropriate for obstructive HCM without valvular pathology 1, but this child has significant valvular disease requiring correction

Post-Operative Management

Following surgery, this child will require:

• Intraoperative transesophageal echocardiography to assess adequacy of septal myectomy and valve function 1
• Follow-up transthoracic echocardiography within 3-6 months to evaluate procedural results 1
• Serial echocardiography every 1-2 years to monitor for residual obstruction, valve function, and progression of hypertrophy 1
• Beta-blocker therapy to manage residual hypertrophic cardiomyopathy symptoms and reduce arrhythmia risk 1
• Continued restriction from competitive sports given the underlying hypertrophic cardiomyopathy diagnosis 1

Critical Pitfall to Avoid

Do not attempt isolated valve replacement without addressing the septal hypertrophy. Undiagnosed or untreated hypertrophic obstructive cardiomyopathy during aortic valve procedures can lead to challenging hemodynamics in the peri-deployment phase, including acute pulmonary edema and hemodynamic collapse. 3 The dual obstruction must be addressed simultaneously for optimal outcomes.